Vol. 11(9), pp. 127-142, October-December 2019 DOI: 10.5897/JENE2019.0799 Article Number: A3C45E862300 ISSN 2006-9847 Copyright © 2019 Author(s) retain the copyright of this article Journal of Ecology and The Natural Environment http://www.academicjournals.org/JENE Full Length Research Paper Forest land use and native trees diversity conservation in Togolese mega hotspot, Upper Guinean, West Africa Kossi Adjossou1*, Fifonsi Ayélé Dangbo1, Tossimidé Houngbedji3, Komla Elikplim Abotsi1, Donko Koudzo Koda2, Atsu Kudzo Guelly2 and Kouami Kokou1 1Laboratoire de Recherche Forestière, Université de Lomé, Togo. 2Laboratoire de botanique et écologie végétale, Université de Lomé, Togo. 3Institut Togolais de Recherche Agronomique, Togo. Received 14 September, 2019; Accepted 22 October, 2019 In tropics, species diversity in agricultural systems is often assessed without distinction between native and exotic species. However, the conservation value of an ecosystem depends on its richness in native species. This study was conducted to determine the conservation value of agricultural systems in Togo megahotspot, one of the species-rich sites in Upper Guinean. Specifically, the study compares fallow systems (FS), coffee systems (COFS), cocoa systems (COCS) to forest relics (FR) on the one hand, and on the other hand the agricultural systems (FS, COFS, COCS) between them base on natives tree species diversity and composition. Sites have been selected to represent different forest lands use types. Plots (n = 233) of different sizes (400, 500 and 625 m²) were used for data collection. In each plot, all living trees (DBH ≥ 10 cm) were counted. Rarefaction, generalized linear models (GLM) and ecological distance approach were used to standardized and compare the data. A total of 183 species were recorded, of which 42% were absent from the agricultural plots. Difference in diversity index were significant between the FR and agricultural systems (p<0.001), but not between agricultural systems (p=0.23). Guineo-Congolian climax and endemic species were seriously under threat. The study poses a real problem of regeneration dynamic of these species in human-dominated landscapes that requires further specific work. Key words: Rainforests, agricultural practices, biodiversity conservation, Reducing Emissions from Deforestation and Forest Degradation (REDD+), Togo, Upper Guinean. INTRODUCTION Agroforestry is generally defined as association of trees especially traditional ones, play an important role as with crops and livestock. There are several agroforestry refuges of tropical biodiversity by providing habitat for practices; including shade trees with perennial crops many species of plants and animals in human-dominated such as coffee and cocoa. Several studies on tropical landscapes (Cicuzza et al., 2011; Cassano et al., 2012; ecosystems have shown that agroforestry systems, Maas et al., 2015; Gras et al., 2016). Thus, it is widely *Corresponding author. Email: [email protected]. Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License 128 J. Ecol. Nat. Environ. accepted that agroforestry is the only alternative to meet addition, the few studies carried out on the conservation the ecological and economic challenges posed by slash- value of agroforestry systems in Africa have taken into and-burn agriculture practices (Fischer and Vasseur, account exotic species, that is, species richness and not 2000). These ideas have contributed immensely to the forest species richness (Aerts et al., 2011). In Cameroon, growth of agroforestry projects across the tropics in the for example, cocoa systems are rich with 206 species of recent decades. Some of these studies have also trees while this richness included one third of exotic highlighted the importance of these systems for carbon species with densities which double those of native sequestration (Schroth and Harvey, 2007). Today, forest species (Sonwa et al., 2007). The disadvantage is that, policies of many counties aim at increasing forest areas exotic species can greatly influence diversity index whose through the promotion of agroforestry systems for carbon calculations are often based on abundance data, with as and biodiversity. The conservation of this latest consequence the overestimation of the conservation (biodiversity) is a critical component of the development value of these agroforestry systems. Otherwise, human and implementation of UN-led Reducing Emissions from land use causes major changes in species abundance Deforestation and Forest Degradation (REDD+) and composition, yet native and exotic species can (Bustamante et al., 2016). However, in recent decades, exhibit different responses to land use change. Native there have been major changes in agroforestry practices species populations generally decline in human‐impacted in the coffee-cocoa sector around the world because of habitats while exotic species often benefit (Jesse et al., the declining productivity due to tree age, soil poverty and 2018). Exotic species are often generalist species or increased disease. In West Africa, facing declining species that adapt easily to human disturbance. It is often productivity, traditional cocoa and coffee systems had those taxa that are of the highest priority for conservation, been the subject of several managements by producers such as regional forest endemics, that are the most to make them more productive. These included the extinction prone in modified tropical landscapes (Gardner rehabilitation and replanting of fields, the use of Upper et al., 2009). For these reasons, ecologists think that a Amazon hybrid cocoa without shade, intensification by better indicator of the conservation value of agroforest the planting of additional trees and fruit trees, and the systems would be the forest species richness. Thus, to conversion of secondary forest and fallow areas to estimate accurately the value of modified landscapes for agroforestry and monoculture plantations (Wessel and conserving regional forest biodiversity we need to know Quist-Wessel, 2015). These changes in agroforestry the proportion of species that inhabit human-modified management practices and their potential impact on systems that were also inhabitants of the original forest tropical biodiversity raise today the question of the landscape (Gardner et al., 2009). conservation value of agroforestry systems that requires The Upper Guinean forests are among the 25 most research, especially in Africa where the conservation important hotspots in the world (Poorter et al., 2004). value of agroforestry systems are poorly evaluated They are estimated to contain 2,800 forests plant species compared to Asia or Latine America (Fischer and among which 650 are endemics, and about 400 are Vasseur, 2000; Paruelo et al., 2001; Siebert, 2002; Rolim considered rare. Within Upper Guinean, three areas of and Chiarello, 2004; Ashley et al., 2006; Harvey et al., high diversity are distinguished and need protection and 2007; Schroth and Harvey, 2007b; Philpott et al., 2008; attention (Poorter et al., 2004). Togo megahotspot is one Chazdon et al., 2009; Gardner et al., 2009; Wanger et al., of the three areas of high diversity in Upper Guinean that 2009; Feeley and Silman, 2010; Hoehn et al., 2010; owes its immense biodiversity to its past climate but also Williams Guillén and Perfecto, 2010; Cicuzza et al., 2011; to the current ecological conditions of humidities and fogs Tscharntke et al., 2011; Cassano et al., 2012; Pelletier et which contributed to the installation of a great diversity of al., 2012; Dawson et al., 2013; Bustamante et al., 2014; forest communities (Akpagana, 1989). These forests of Maas et al., 2015; Sariyildiz et al., 2015; Sharma and the mountains of Togo have been assigned to agriculture, Vetaas, 2015; Valencia et al., 2015; Barsoum et al., particularly for shifting, coffee and cocoa cultivation, 2016; Gasperini et al., 2016; Gras et al., 2016; ; Farah et which has led to repeated clearings. The conservation of al., 2017; Almazán-Núñez et al., 2018; Benítez-Badillo et biodiversity in this area largely depends of a deeper al., 2018; Jesse et al., 2018; Rodrãguez-Echeverry et al., comprehension of the impact of forest land-use types on 2018; Santos-Heredia et al., 2018). Few studies in Africa native species diversity. However, this information is now compare agriculture systems to natural forests and absent today on this area. Togo Mountains vegetation each other to assess their conservation value based on was the subject of several works (Aké Assi, 1971; Brunel, forest species richness (Eilu et al., 2003; Augusseau et 1977, 1978; Akpagana, 1989, 1992; Guelly, 1994; al., 2006; Bobo et al., 2006; Norris et al., 2010; Pinard et Adjossou, 2004, 2009; Kokou et al., 2008; Adjossou and al., 2013). In Africa, several studies have been conducted Kokou, 2009;). Recent works have been focused on on agroforestry systems for coffee and cocoa. However, agroforestry systems in the area (Adden et al., 2016, these studies have rather addressed issues related to the 2018; Koda et al., 2016; Adden et al.). Nevertheless, decline in productivity and the socio-economic aspects of there is an important lack of information on conservation these systems (Wessel and Quist-Wessel, 2015). In value of forests land-use types of this area. The present Adjossou et al. 129 study is significant in providing clear answers to introduced into the forest zone. Until 1989, most